Influence of aspect ratio on the natural convection and entropy generation in rectangular cavities with wavy-wall

The natural convection in rectangular cavities with different aspect ratios and hot wavy walls was investigated through numerical simulations. The undulation of the cavity is fixed to three (03) however the Rayleigh numbers is ranging from 105 to 108. Second law of thermodynamics was also applied to predict the nature of irreversibility in terms of entropy generation. Heat transfer between vertical walls occurs by laminar and turbulent natural convection. The computations have been performed using FLUENT 6.3.26 by employing the k-ε model for turbulence. Based on the obtained dimensionless velocity and temperature values, the distributions of local entropy generation due to heat transfer and fluid friction are determined. The distributions of the stream function, static temperature, the total entropy generation and the local Bejan number are plotted for different aspect ratios Rayleigh number, and irreversibility coefficients 10-4< <10-2. The total entropy generation is found to increase with increasing aspect ratios.